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JPH10174191

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DESCRIPTION JPH10174191
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker diaphragm having a light weight, high elasticity and high internal loss.
[0002]
2. Description of the Related Art Conventionally, as materials used for diaphragms for speakers,
metal materials such as aluminum, titanium, beryllium and magnesium, ceramic materials such
as alumina and boron, and pulp and paper such as wood pulp and bast fibers Materials, synthetic
resins such as polypropylene and reinforced plastic materials are used.
[0003]
Recently, a door mount speaker for vehicles and a speaker for PA used outdoors are required to
be waterproof to a shampoo solution for washing a car and rain water, etc., so a diaphragm for a
speaker mainly made of conventional paper pulp From the above, the adoption of diaphragms for
speakers of synthetic resins such as olefin resins such as polypropylene and polymethylpentene,
thermosetting resins such as phenol resin and epoxy resin, and engineering plastic resins such as
liquid crystal polymer is increasing.
[0004]
However, since the wettability of the surface of the olefin-based synthetic resin is poor due to the
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poor adhesion, the vibration for the speaker is required unless special treatments such as corona
surface treatment and low temperature plasma treatment are performed. There is a problem that
the adhesion as a board can not be secured.
In addition, even when a filler is added, there is also a problem that the bending elastic modulus
of the material is low and the reproduction frequency band as a speaker is narrow.
Furthermore, in the case of polypropylene resin, there is also a problem that there is no
sharpening on the sound quality in a high frequency band because the internal loss is large.
[0005]
In addition, phenol resin and epoxy resin have poor formability to the shape of the speaker
diaphragm, and it takes a long time to form, and there is a problem that productivity as the
speaker diaphragm is poor and internal loss of the material is low. The peak pressure of the
sound pressure is severe, the harmonic distortion is also large, and the sound quality is offensive.
[0006]
In addition, liquid crystal polymers have a wide reproduction frequency band and adequate
internal loss, but have poor adhesion as with olefin resins, and they have the problem that they
can not be used for general-purpose speakers because the materials are expensive. .
[0007]
The present invention solves these problems and provides a speaker diaphragm with good sound
quality and performance and good productivity at low cost.
[0008]
[Means for Solving the Problems] In order to solve the above problems, the speaker diaphragm of
the present invention is formed by heating and melt-forming a resin composition comprising a
polybutylene terephthalate resin and an acrylonitrile butadiene styrene copolymer resin. It is
molded in a cone shape, and is excellent in adhesiveness as a diaphragm for a speaker, and can
provide an extremely high productivity by molding.
[0009]
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2
The invention according to claim 1 of the present invention is a resin composition formed by
blending a polybutylene terephthalate resin and an acrylonitrile butadiene styrene copolymer
resin, which is formed by heating and melt forming into a cone shape. The speaker diaphragm
having excellent adhesion, heat resistance, moldability, dimensional stability during molding, and
impact strength can be obtained by adopting the above-described structure.
[0010]
The invention according to claim 2 of the present invention is one in which a filler selected from
mica, talc and graphite is blended as a filler of the thermoplastic resin according to claim 1 in a
weight ratio of 5% or more. It can be done.
[0011]
Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a partially cutaway perspective view of the main part of a speaker diaphragm according
to an embodiment of the present invention.
Various thermoplastic resin compositions described as resin compositions 1 to 3 in Table 1 were
prepared by blending an acrylonitrile butadiene styrene copolymer resin, a polybutylene
terephthalate resin, and an inorganic filler as a speaker diaphragm. The resin A described in
Table 1) as Comparative Examples 1 to 3 is heat-melted from the neck portion of the diaphragm
A for the diaphragm A (16 cm diameter and 0.25 mm surface thickness) shown in FIG.
(Comparative example 3 can not be injection molded, so it is formed by press molding using a
heat press die).
[0012]
At this time, the resin compositions 1 to 3 completely flow at a melt flow rate of 50 g / min or
more, and the molding time of the diaphragm A to the shape of the resin compositions 1 to 3 and
comparative examples 1 and 2 is In Comparative Example 3 took 15 minutes.
[0013]
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Next, a 4 × 20 mm test piece was punched out from the diaphragm along the radial direction,
and the sound velocity and internal loss (tan δ) were measured by the vibration reed method.
In addition, test pieces were prepared according to the specifications in (), and the heat distortion
temperature (ASTM D 648) and the flexural modulus (AS D M 790) were measured.
Further, in order to measure the adhesive strength, the adhesive strength was measured by
adhering to a cotton No. 2 canvas with a chloroprene phenolic adhesive (Diabond Industry Co.,
Ltd. DB-1600w) on the peripheral portion of the diaphragm.
The results are shown in (Table 2).
[0014]
As is clear from the measurement results of Table 2 above, the speaker diaphragm of this
embodiment using the resin compositions 1 to 3 is as good as the comparative example in the
material physical properties and acoustic characteristics, and is adhered It is excellent as a
speaker diaphragm for improving the adhesive strength of the bond with the edge B in FIG. 1 and
the adhesive strength of the bond with the voice coil bobbin (not shown). Was confirmed.
[0015]
As described above, the speaker diaphragm of the present invention is excellent in adhesion, and
can provide a speaker diaphragm which can be efficiently supplied at low cost with high
productivity.
[0016]
Brief description of the drawings
[0017]
1 is a partially cutaway perspective view of one embodiment of the speaker diaphragm of the
present invention
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